The Safety Effectiveness of the Audio Tactile Profiled Markings Programme Steve James The Safety Effectiveness of the Audio Tactile Profiled Markings Programme Steve James NZ Transport Agency ABSTRACT Over the period 2006 to 2012, the New Zealand Transport Agency installed significant lengths of Audio Tactile Profiled (ATP) markings. In general these markings were on higher volume, higher collective risk state highways used for long distance travel, with the primary focus on State Highway 1. Questions have been asked in some quarters regarding the value of this initiative, given the ongoing cost of maintaining these markings, and in particular replacement costs following resurfacing. This paper explores the effectiveness of this ATP strategy in reducing fatal and serious injury crashes. Given the safety benefit achieved there is a clear case for maintaining these installations going forward, and extending the programme further as funding becomes available. 1 The Safety Effectiveness of the Audio Tactile Profiled Markings Programme Steve James 1. INTRODUCTION Audio Tactile Profiled (ATP) road markings are a type of long life road marking product, typically plastic “lumps” (called blocks or ribs). The ribs, which are usually 7mm in height, 50mm deep and 150mm long, are laid onto the road surface, at 250mm centres. When vehicle tyres run over the ATP, it provides an audible and tactile notification alerting the driver of a possible lane departure. The ATP markings also provide additional delineation, especially in wet and dark driving conditions. The NZ Transport Agency (NZTA) has been installing ATP markings for many years at high risk rural locations. However, following successful trials in the Waikato/Bay of Plenty, a wider application of ATP markings was specifically funded in mid/late 2008. By the end of 2012, approximately 3,300 linear kilometres of ATP has been installed along 1,300km of the state highway network (approximately 12%), with a mixture of white edgelines and centrelines and yellow centrelines. Marsh (2009) looked at the decision to implement the profiled markings programme and provided an overview of associated background, trialling and research. This paper compliments the Marsh (2009) paper by providing evidence of the crash reductions throughout New Zealand where ATP has been installed to date. 2. BACKGROUND The New Zealand road safety strategy from the last decade, Road Safety to 2010 (Ministry of Transport, 2003) included a goal of no more than 300 deaths and 4,500 hospitalisations by 2010. The strategy was developed by the National Road Safety Council (NRSC) which was made up of representatives from Ministry of Transport, Accident Compensation Corporation (ACC), Local Government New Zealand (LGNZ), Police, Transit New Zealand, Transfund New Zealand and the Land Transport Safety Authority. The latter three agencies have since been incorporated into the New Zealand Transport Agency (NZ Transport Agency. In the year previous to the release of the 2003 strategy there were 404 deaths and 6,670 hospitalisations; the lowest road toll in 40 years. In 2010, the road toll was 375 (Ministry of Transport, 2013): in 2011 it was 284. The rolling road toll actually got down to 300 deaths for the past 12 months in October 2011. This means the 2003 goal of no more than 300 deaths by 2010 was reached only 10 months late. New Zealand’s latest road safety strategy is called Safer Journeys 2020 (Ministry of Transport, 2010). It does not contain any targets. Instead it has a long-term goal which is set out in its vision “A safe road system increasingly free of death and serious injuries”. The strategy is based upon taking the safe system approach; acknowledging that while we cannot prevent crashes from occurring, we can stop many of them resulting in death or serious injury. This approach requires working across four elements of the road system; safe users, safe roads and roadsides, safe vehicles and safe speeds. ATP is used as part of safe roads and roadsides. 2 The Safety Effectiveness of the Audio Tactile Profiled Markings Programme Steve James The safety performance of ATP markings has been the subject of a number of literature reviews (Mackie & Baas, 2007; KiwiRAP, 2008; Hatfield, Murphy, Soames, Wei Du, 2008; Marsh, 2009), and there is considerable variation surrounding the level of crash reductions claimed. In the case of edge (shoulder) rumble strips, these are reported as reducing run-off-road crashes by 20% to 80%, while centreline rumble strips have been found to reduce head-on and side-swipe crashes of between 21% and 37%. However, many of these findings came from studies in the United States (USA) where a different process is used to form the rumble strips. KiwiRAP (2008) identified that ATP markings could bring about one of the greatest possible reductions in injury crashes (20% to 45%), while also assisting with the management of driver fatigue and inattention (Edgar, Mackie, Baas, 2009). An evaluation by the Australian Road Research Board (ARRB) of reported crash savings from studies of profile edge lines, noted the selection of a 20% injury crash reduction with a medium confidence level (Australian Road Research Board, 2006). Closer to home Mackie and Baas (2007) investigated the cost effectiveness of treating a larger proportion of New Zealand’s roads with ATP edgelines and no overtaking centrelines, using a default crash reduction of 25% as the best estimate from reviewed literature. Based on the significant safety benefits expected, the NZ Transport Agency developed a business case and a national strategy (Brodie, 2008) to increase the installation of ATP markings on New Zealand state highways from mid 2008. The business case took a conservative approach, assuming an overall injury crash reduction rate of 15%, the resulting BCR was 7.2 based upon installation and regular replacement costs. High risk corridors were targeted first by identifying roads with high incidence of crashes or higher volumes (Brodie, 2008). Treatment lengths were guided to a large extent by identifying the higher collective and personal risk routes outlined in KiwiRAP (2008). It was agreed that continuous installation of ATP markings along significant lengths of highway would be favoured over a series of localised or spot treatments at crash blackspots. Guidelines for using audio tactile profiled (ATP) roadmarkings (2010) are a document produced by the NZ Transport Agency that includes the key specifications and recommendations for ATP roadmarking use. A 1m wide minimum shoulder width should be provided (ideally 1.5m) and kept clean to ensure effective space for cyclists. Narrower shoulders can be provided to include a continuous treatment, but careful consideration of cyclists must be carried out. The impact of noise must also be carried out where noise disturbance is likely. It is usual to not include ATP roadmarkings within 100m of a residential dwelling. 3. MAINTENANCE ISSUES One of the greatest risks to the continued rollout of a national ATP marking initiative relates to the ongoing maintenance needs, particularly in a constrained economic environment. There is a need to ensure that relevant information about maintenance issues and the associated costs is readily available to those responsible for removing, maintaining and reinstalling ATP markings. Part of this also involves ensuring that operational managers are well informed of the associated safety benefits. The results of the safety benefits for the national installation of ATP 3 The Safety Effectiveness of the Audio Tactile Profiled Markings Programme Steve James markings included within this paper will be shared with those operational managers/asset managers. Previous research (Mackie & Baas 2007) has demonstrated that the benefits of ATP markings outweigh the cost of installation and maintenance except on very lightly trafficked roads. The business case model assumed the rumble strip replacement cycle averaged four years on busy highways and 10 years on lower volume highways (Mackie & Bass, 2007). Some existing ATP installations have been in place now for over six years and are still very effective. A new research project has been commissioned by NZTA, entitled “Optimum renewal of audio tactile profiled markings”, that will hopefully include greater analysis on the wear and tear of ATP and how to extend the life of it. This is due to be published is 2014. 4. METHODOLOGY FOR CRASH ANALYSIS In order to provide a suitable period for analysis after the installation of ATP markings, it was decided to only focus on those installations that have been installed for over one year, so that enough crash data is available to analyse. Where ATP markings have been installed on at least 50% of any one route station, then the entire route station has been analysed for injury crashes. Each route station with ATP has been set up in the crash analysis system (CAS) as a “site of special interest”. This allows for the site to be monitored; the data extracted from CAS is used to provide a before and after analysis. The CAS database was examined, and all injury crashes from 2003 to December 2012 inclusive were included in the monitoring analysis, so that at least 3 years of crash data was available before installation of ATP. The number of crashes before the installation date has been noted, together with the predicted number of crashes after the installation date of the ATP markings. This is then compared against the actual number of crashes after installation of the ATP to give either